Try inheriting from ADefaultPawn, it allows for replacement of the movement component with a custom one because it has the needed FName for the component replacement
then you can use code like this:
ACustomPawn::ACustomPawn(const FObjectInitializer& ObjectInitializer) : Super(ObjectInitializer.SetDefaultSubobjectClass<UCustomMovementComponent>(MovementComponentName))
{
PrimaryActorTick.bCanEverTick = true;
}